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PAL Questions: 834 - Garden Tools: 346 - Recommended Websites: 680

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Keywords: Hoya bella, Potted plants, Tropical plants, House plants

PAL Question:

My Hoya bella was recently moved outside. It flowered nicely, but now the leaves are a light yellow/green and the soil surface in the pot is covered with moss. What is wrong and what can I do?

View Answer:

Here is some information I found in the book, Subtropical plants: a practical gardening guide (by Jacqueline Sparrow and Gil Hanly, 2002, p. 107), quoted below:

Hoyas do very well in pots. They need bright light, but not sun...Hoyas strike fairly easily from cuttings, taken at the warmest time of the year.

About the yellowing of the leaves...I am pretty confident that this is due to the plant getting too much water (rain, whatever source, while it was outdoors) and the soil not drying out, which also explains what happened to the top of the soil--the moss or algae growth there. I would just gently scrape off the soil surface and put a thin layer of potting soil over it. If the plant starts getting what it needs again (as it did before it was put outdoors), it will hopefully return to its former healthy self.

During its growing season, Hoya bella prefers temps between 64 and 68 degrees; during its rest season, 59 degrees is the recommended minimum temperature (so here in Seattle, right next to a window may be too cold).

University of Florida provides additional information about Hoya bella.

Season All Season
Date 2008-01-10
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Keywords: Lonicera, Poisonous plants, Berries

PAL Question:

Are the berries of wild woodbine poisonous?

View Answer:

Wild woodbine or woodbine is Lonicera periclymenum. But many species of Lonicera are found in the United States.

For photos of L. periclymenum, see the two sites below:
West Highland Flora
Paghat's Garden

North Carolina University's poisonous plant website indicates that the berries of Japanese honeysuckle (Lonicera japonica) are poisonous.

Toxic Plants of North America (G.E. Burrows and R.J. Tyrl, 2001, pp.321, 322) says that while some species of Lonicera (i.e., L. involucrata) are edible, the rest are associated with digestive tract problems in children (nausea, vomiting, diarrhea), especially the European species. In the U.S., on the other hand, records of complaints are not often associated with records of clinical signs.

Season All Season
Date 2006-12-08
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Keywords: Hedera hibernica, Hedera helix, Invasive plants--Control, Noxious weeds--Washington

PAL Question:

I am trying to write a letter about English ivy in order to get it removed from a public library. Is it a noxious weed?

View Answer:

Washington State and King County noxious weed information is updated annually. Currently, three cultivars of Hedera helix and one cultivar of Hedera hibernica are Class C Noxious Weeds in the State of Washington.

Here is the link to descriptions of these four types of English ivy.

Class C Noxious Weeds are weeds that are already widespread; removal is NOT required by law. However, individual counties can adopt removal programs as they see fit. Here is the complete list of Class C noxious weeds in Washington.

King County also has more information on a website about noxious weeds.

King County does not require control or eradication of any of the four English ivy cultivars. Although control is strongly recommended, it is not required.

Season All Season
Date 2008-01-10
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Keywords: Clerodendrum, Woody plant propagation

PAL Question:

When and how can I propagate a glorybower? There are suckers coming up at the base of the plant.

View Answer:

Regarding propagating Clerodendrum trichotomum (harlequin glorybower), the book Trees and Shrubs Hardy in the British Isles Vol. I (by W. J. Bean, 1981, p. 667) says that shrubs can be propagated by root-cuttings, or by the young suckers which frequently spring from the roots.

Since you mentioned that there were suckers (gardening term) coming up around the plant, it is most likely the species is C. trichotomum and not C. bungei (one of the others commonly grown in our climate). C. bungei, according to the same source, should be divided in the spring.

Another source, Flora, Vol. 1, (chief consultant, Sean Hogan, 2003, p. 393) says regarding Clerodendrum (genus-level information) that propagation is done by sowing seed in spring or by taking cuttings of half-hardened wood during winter or summer.

Season All Season
Date 2006-03-02
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Keywords: Germination, Propagation, Acer

PAL Question:

I am interested in the seed germination requirements of Acer triflorum and Acer griseum.

View Answer:

There is information in The Reference Manual of Woody Plant Propagation by Michael Dirr and Charles Heuser (Varsity Press,2006):

Acer triflorum seed is "doubly dormant and when fall planted will germinate the second spring and sporadically thereafter. Seed, unfortunately, is often not sound [...] Nine months warm followed by 3 months cold gave reasonable germination. If seed is received dry it may be prestratified for 6 months and then sown. Germination is less than 1% the first year but is very good the second."

The authors state that with Acer griseum, "the biggest problem is poor seed quality" (between 1 to 8% viability). Also, seed production from an individual tree varies widely from year to year. "Seeds are doubly dormant and if fall planted require 2 years, some germinating the third year and beyond. The pericarp wall is extremely tough and dormancy is caused by a physical barrier as well as internal embryo conditions." Dirr says that he has cold-stratified seed for 90 days, split the fruit wall to extract the embryos, and planted them in vermiculite with a fair amount of success. Growing this tree from cuttings is considered extremely difficult, and grafting (onto seedling Acer griseum seems to be the easiest propagation method.

Season All Season
Date 2008-01-10
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Keywords: Schisandra chinensis, Woody plant propagation, Herbs

PAL Question:

How can I propagate the Schisandra fruit vine?

View Answer:

It does not sound like the easiest plant to propagate from seed. Cuttings or layering might be less challenging. The Maine Organic Farmers and Gardeners Association has a guide to growing Schisandra, including propagation information. Here is an excerpt:
"Propagate Schisandra by seed, cuttings or layering. The seeds can be planted in prepared seedbeds 1/4-inch deep in the fall soon after they ripen or indoors in March. Dry seeds need to be soaked overnight. In Herbal Emissaries: Bringing Chinese Herbs to the West, Steven Foster and Yue Chongxi say that in China an acid scarification process is sometimes used, because the seeds have such a hard coat."

Plants for a Future's database includes propagation details for Schisandra chinensis:
"Seed: best sown in the autumn in a cold frame. Pre-soak stored seed for 12 hours in warm water and sow in a greenhouse in the spring. Germination can be slow and erratic. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in light shade in the greenhouse for their first 2 years. Plant them out into their permanent positions in early summer.
"Cuttings of half-ripe wood, 5 - 8cm with a heel, August in a frame. Overwinter in the greenhouse and plant out in late spring.
"Layering of long shoots in the autumn."

Season All Season
Date 2008-01-17
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Keywords: Vegetable varieties, Tomatoes

PAL Question:

What are the best types of tomatoes for the Pacific Northwest climate?

View Answer:

In Growing Vegetables West of the Cascades (Steve Solomon, 2000, pp.241,242), the author notes that any tomato advertised in a seed catalog as needing more than 72 days for maturity will not likely reach a ripe old (tasty) age in our region. Solomon suggests purchasing seed only from regional companies like Territorial Seed Co. or West Coast Seeds. The varieties he recommends are
1. some that ripen early in the Willamette Valley (bred by Jim Baggett) = Oregon 11, Oregon Spring, Santiam, and Gold Nugget
2. slicers = Fantastic Hybrid, Pic Red, Early Cascade, and Kootenai
3. cherry = most are prolific here, but Solomon prefer's Jim Baggett's Gold Nugget

Here is a link to an article by Chris Smith in the Seattle Post-Intelligencer (01-19-2006) that introduces some new tomatoes and other vegetables for 2006.

Seattle Tilth has an article by Kirsten DeLara (2011) called "Grow Great Tomatoes in Seattle" which includes a list of the author's favorite varieties for our area. Also check Seattle Tilth's annual list of tomatoes available at their sales, and their reports on tomato tasting results.

Mother Earth News published an article on the best Pacific Northwest varieties in February/March 2010.

Season All Season
Date 2008-01-17
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Keywords: Plant exchanges and donations, Seed exchanges

PAL Question:

How can I find out about plant exchanges? I also have some plants I want to donate.

View Answer:

There are several places you can go for this information.

The Garden Web has a page with Pacific Northwest plant exchange information.

King County has a Native Plant Salvage program through which you might be able to make some contacts or find homes for plants you want to donate.

Plant Amnesty has an Adopt-A-Plant program.

Community centers, places of worship, and public schools also appreciate plant donations; contact some in your area and see if they want what you have. People also post plants to share on Craigslist.org and Freecycle.org.

The Seattle Times published this article about plant swaps and exchanges.

Finally, various plant societies/gardening organizations have plant exchanges. Here is a link to information about such organizations:
Miller Library's Organizations List

Season All Season
Date 2006-12-08
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Keywords: Plant identification, Betula

PAL Question:

Are there any tree identification guides online? In particular, I am interested in weeping birch.

View Answer:

For several excellent images of weeping birch (Betula pendula), go to Oregon State University's landscape identification site at http://oregonstate.edu/dept/ldplants/ and click on Betula in the bright orange box.
Betula pendula is toward the bottom of the page.

Also try Virginia Tech's tree identification page.

Here are some other online tree identification guides:
http://www.oplin.org/tree/
http://www.na.fs.fed.us/spfo/pubs/silvics_manual/table_of_contents.htm
http://selectree.calpoly.edu/

Season All Season
Date 2008-01-17
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Keywords: Crocus, Flowering of plants, Narcissus

PAL Question:

Many of my crocus and daffodils (especially crocus) didn't flower this year. They don't seem to be in need of separating - none of them have been in the ground for over 3 years and I don't think I overfertilized. Otherwise they seem quite healthy. What might be the problem?

View Answer:

The most common reasons that hardy bulbs like crocus and daffodils fail to flower are these:

1. Planting location: they need to be planted in full sun.
Bulbs; a complete handbook of bulbs, corms, and tubers (by R. Genders, 1973)

2. Drainage or heat: spring flowering bulbs planted in poorly drained soil or too near a heated basement (where heat from the structure warms the soil and interferes with the bulbs' necessary cold treatment) will rot or simply fail to flower.
Daffodils for Home, Garden and Show (by D. Barnes, 1987) 3. Fertilization: high nitrogen fertilizers encourage lush green growth and discourage flowering.
Daffodils for American Gardens (by B. Heath, 1995)

Season Spring
Date 2006-03-06
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Keywords: Frost, Hardy plants, Plant diseases--Diagnosis, Rhododendron

PAL Question:

A friend in Illinois has sent a photo this spring of a very healthy looking rhododendron - leaf buds fully elongated and beginning to unfurl, while the green, blunt flower buds remain unopened. The flower buds don't look brown, diseased, frozen or injured, but they remain tightly closed, foliage bud growth preceding blooming. He says he has 6 plants doing the same this month. Possible reason?

View Answer:

Though we can't diagnose plant problems by phone/email, early autumn frosts can inhibit flowering and not all buds are equally affected.

"Autumn frosts: These can lead to damage...if they either occur in early autumn or immediately after a late season warm spell. Continental climates with extremes of heat and cold are more likely to suffer sudden temperature changes than those with maritime climates...A sudden temperature drop will catch a plant before it has had a chance to reach maximum hardiness and it may suffer accordingly, even if normally perfectly able to withstand such a temperature in mid-winter...Speed of ripening varies considerably...There is also a variation in the hardiness of flower buds compared to foliage and growth buds. Commonly, flower buds may be as much as 10 F. less hardy than foliage..."
(Source: The Cultivation of Rhododendrons, by P. Cox, 1993, p. 119-120)

On the other hand, there might be something unusual about your friend's particular location. He/she might want to call a local Master Gardener and ask whether they're aware of anything abnormal. To locate Master Gardener clinics in various Illinois counties, go to http://www.extension.uiuc.edu/mg/ui-hort-links.html.

Season Fall
Date 2008-01-17
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Keywords: Pruning shrubs, Rhododendron

PAL Question:

A friend was told that pinching out growth buds before they begin to elongate as a means of shaping young rhododendrons would only stimulate buds further down the stems that were less than 4 years old - older than that and the growth buds would no longer be viable. I cannot find any information to suggest 4 years viability of dormant buds to be true, or untrue. Can you help?

View Answer:

Though pinching encourages multiple branching lower down the stem, I find no reference to it being done at a particular age.

“This practice (pinching) is recommended for most larger rhododendrons until they reach flowering size...”
(Source: A Plantsman’s Guide to Rhododendrons, by K. Cox, 1989, p. 101)

That statement indicates a younger plant, but the author then mentions several exceptions.

Here is some how-to information about pruning online:
7 Solutions to the Too-Big Rhododendron.

Season Spring
Date 2008-01-17
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Keywords: sericulture, silkworm, Morus

PAL Question:

What type of mulberry do silkworms eat, and where can I find this tree (I need leaves for feeding the silkworms)?

View Answer:

Silkworms will eat any species of Morus, though white mulberry (Morus alba) is their preferred food source. See the following information from Union County College's biology department and University of Arizona's Center for Insect Science Education for further details.

I understand you are looking for a tree source. I wonder if you actually plan to plant the tree, or if what you really need is access to mulberry leaves. Numerous mail order nurseries carry Morus alba, Morus alba tatarica, Morus rubra, and Morus nigra, and in fact you may find local nurseries with trees, too--it's just that they don't keep an online inventory because it changes too frequently. You can search Plant Information Online for mail order sources. I did a quick search on Morus alba, and found several nurseries that carry it.

If you simply want leaves, you may want to check Arthur Lee Jacobson's book, Trees of Seattle, which lists locations of trees in both private and public gardens. You would, of course, need to obtain permission to harvest any leaves.

This website offers information on real and artificial food sources for silkworms.

Season All Season
Date 2006-03-16
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Keywords: fastigiate trees and shrubs, Cornus kousa, Trees in cities

PAL Question:

Can you recommend some narrow or fastigiate trees for the space between our house and the house next door? The space is about 14 feet wide. Will Cornus kousa 'National' work?

View Answer:

From what the experts say, Cornus kousa grows 20—30 feet high and wide in cultivation. They can grow to twice that size in the wild.

I found this and other information that might help you in the sources below:
1. Trees and Shrubs for Pacific Northwest Gardens, by J. Grant, 1990, p. 71
2. Trees & Shrubs Hardy in the British Isles, by W.J. Bean, 1976, p. 703
3. Manual of Woody Landscape Plants, by M. Dirr, 1998, p. 260
4. North American Landscape Trees, by A. Lee Jacobson, 1996, pp. xiii, 144

The Seattle City Arborist’s Office recommends the following narrow trees:
1. Magnolia grandiflora 'Little Gem' - 15 ft. high, 10 ft. wide. White flowers, evergreen.
2. Malus 'Adirondack' - 18 ft. high, 10 ft. wide. White flowers, red fruit, excellent scab resistance.
3. Malus 'Red Barron' - 18 ft. high, 8 ft. wide. Red flowers, red fruit, yellow fall color.
4. Malus 'Golden Raindrops' - 18 ft. high, 13 ft. wide. White flowers, yellow fall color, abundant yellow fruit.
5. Prunus serrulata 'Amanogawa' - 20 ft. tall, 6 ft. wide. Pale pink double flowers, bronze fall color.

Here are additional sources:

Season All Season
Date 2008-01-17
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Keywords: Soil stabilization, Soil erosion, Slopes (Soil mechanics), Tree identification, Populus

PAL Question:

When a cottonwood tree is cut down, does the stump die, or does it send out shoots that grow into more trees?

And, if a cottonwood tree located on a hillside is cut down, what is the risk of erosion?

View Answer:

As it turns out, some poplars and cottonwoods sucker from the roots and some do not. Determining what kind of cottonwood you have is the key to answering this question.

Identifying tree varieties can be tricky. The best way to get a positive ID is to take a sample to the Hyde Herbarium at the Center for Urban Horticulture (near the University of Washington). It is definitely worth a visit, as it is the only herbarium on the West Coast that serves the public.

Hours, driving directions, how to collect specimens, etc. are at http://depts.washington.edu/hydeherb.

As for your second question, here is what the Washington State Department of Ecology’s Vegetation Management: A Guide for Puget Sound Bluff Property Owners has to say (p.25):
Given the importance of tree cover on potentially unstable slopes and the advisability of retaining them for erosion control purposes, a landowner should explore alternative options to tree removal or topping...[if a tree must be cut] stumps and root systems should be left undisturbed...[to reduce the risk of erosion].

The above document is available online at http://www.ecy.wa.gov/programs/sea/pubs/93-31/intro.html.

A companion website from the Washington State Dept. of Ecology contains a great list of groundcovers, shrubs and trees that will help keep your slope intact if you decide to remove the cottonwood. The website includes a Plant Selection guide.

Season All Season
Date 2008-01-17
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Keywords: Pruning trees, Trees--Care and maintenance

PAL Question:

What is the definition of topping a tree?

View Answer:

The Morton Arboretum Tree-Care Handbook calls topping, “indiscriminately sawing off large branches.” (1994)

According to the Washington State Department of Ecology's Vegetation Management: A Guide for Puget Sound Bluff Property Owners (May 1993, p.23), the practice of topping usually refers to cutting the upper portion of the main leader (trunk) in conifers and to the removal of all branches at a particular height in deciduous trees. Topping is not advised.

Plant Amnesty has loads of information about topping - including why it should not be done - at the following link: 5 Reasons Not to Top.

Season All Season
Date 2008-01-17
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Keywords: Betula, Trees in cities--Seattle, Tree roots

PAL Question:

I have a birch tree in my yard. The roots are causing some buckling in the driveway which I share with my neighbor. My neighbor would like me to take the birch tree out. He is concerned that its roots will harm the foundation of his house and my house. Can you give me some information about this?

View Answer:

The Seattle Department of Transportation, in cooperation with the City Arborist’s Office, has created lists of recommended trees for planting in Seattle. While the DOT is more concerned with street trees (trees planted in the strip of ground between the sidewalk and the street), their recommendations may help you. In addition, since the DOT deals with buckled sidewalks on a regular basis, these lists may account for a problem like yours.

Here is the web address:
http://www.seattle.gov/transportation/treeplanting.htm#recommend

The City Arborist’s Office also has a page of trees that they recommend *with reservations*. (White birch and weeping white birch are on the list.) At the bottom of this list are Prohibited Trees.

Here is that web address:
http://www.seattle.gov/transportation/treeswithreservations.htm

Season All Season
Date 2008-01-17
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Keywords: Lysimachia, Plant care, Growth

PAL Question:

I bought a Lysimachia punctata 'Alexander' (variegated) at a plant sale last weekend. I can't find anything about it in my books. Can you tell me more about it? How tall, invasive or not, best place to plant, anything else you think I should know.

View Answer:

I found information on the website of a local gardener, Paghat, with a detailed description of this form of loosestrife. Although it is not supposed to be as aggressive as the species (L. punctata) or as invasive as L. vulgaris (a noxious weed in King County), I recommend keeping an eye on it. Paghat says:
"'Alexander' has variegated leaves, sage-green with cream borders, and sunny yellow flowers. It purports to be a more restrained version of a flower that in the species form is notoriously invasive and often too aggressive for neighboring perennials. Even 'Alexander,' though comparatively slow growing, eventually becomes a large two-foot by two-foot clump with a big root system that can threaten nearby delicate flowers, so take care what you plant around it."

Season All Season
Date 2006-12-08
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Keywords: Helleborus, Plants in winter, Pruning

PAL Question:

I am noticing that the flower bud shoots for my hellebores (Helleborus x hybridus), are starting to push up above the soil surface. There is still a substantial stand of foliage in good condition.

My question is about pruning. I know I'll need to prune about half the leaves away (I understand that the cut should be made at the base) to give the flowers more visibility. Does it harm the plant to prune it during this cold snap? Does it harm the plant to cut ALL the old leaves off in December as the bud stalks begin to appear?

I would appreciate any guidance you can give me, such as when and how extensively to prune them.

View Answer:

According to Hellebores: a Comprehensive Guide by C. Colston Burrell and Judith Knott Tyler, "all the hybrids maintain their foliage (...) throughout all or part of the winter (...) In any case, as the flower buds begin to stir in the center of the rosettes, it's best to remove all the foliage to make way for the flowers. Nothing spoils the garden display like a tangle of flowers wrestling with winter-burned leaves. The juice is caustic and sometimes causes a rash, so take care when removing the old leaves."

In The Gardener's Guide to Growing Hellebores, Graham Rice and Elizabeth Strangman advise a more time-intensive method:
"The best approach is to cut off some leaves during the autumn and early winter when the garden is put to bed, concentrating on removing dead leaves and any showing signs of blackening (...) By Christmas time they should be thinned out sufficiently to leave a good circle. However, as our winters become windier it may be wise to remove them entirely at this stage. (...)Thin the leaves further as the flower stems emerge, then just before they are in full flower remove all the old leaves. (...) To compensate for the removal of the last of the leaves the plants deserve a good mulch." They go on to suggest compost or a mulch of leaves for this purpose. The cold snap is unlikely to harm even recently pruned hellebores, as they seem to thrive in the cold.

Season Winter
Date 2009-12-09
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Keywords: Chionanthus

PAL Question:

Which varieties of fringe tree have glossy leaves? I am especially interested in a comparison between C. virginicus and C. retusus.

View Answer:

More than one variety of fringe tree (Chionanthus) is described as having lustrous leaves. According to Michael Dirr's Dirr's Hardy Trees and Shrubs(Timber Press, 1997), Chionanthus retusus has "3- to 8-inch long, lustrous dark green leaves," while C. virginicus has "3- to 8-inch long leaves [which] vary from medium to dark green, with various degrees of gloss."

If you wish to see images, you can search Google images with the different species names. Oregon State University's online guide to Landscape Plants has good detailed images and descriptions of these two species of Chionanthus.

Season All Season
Date 2008-01-17
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Keywords: vegetables--preservation, fruit--preservation

PAL Question:

I've never done any canning before but now that I've started growing more of my own fruit and vegetables I want to know how to do it safely! I've heard about a few different canning processes (water bath and pressure). Is one method or another best for certain types of food?

View Answer:

There is a very helpful article for canning beginners in the July/August 2012 issue of Urban Farm magazine, entitled "Oh, You Know I Can!" by Lindsay Evans. You mention the only two canning methods which the article says are approved by the U.S. Department of Agriculture as safe, water-bath and pressure canning. Their National Center for Home Food Preservation has extensive information. Here are excerpts:

Proper canning practices include:

  • carefully selecting and washing fresh food,
  • peeling some fresh foods,
  • hot packing many foods,
  • adding acids (lemon juice or vinegar) to some foods,
  • using acceptable jars and self-sealing lids,
  • processing jars in a boiling-water or pressure canner for the correct period of time.

Methods that are NOT recommended are open-kettle and steam canning, or using the oven or microwave to process filled jars.

The article has a handy list of which foods work best with water-bath canning, and which with pressure canning. Generally, high acid foods (pH level of 4.6 or less) can be processed with the water-bath method and low acid foods (pH of 4.6 or more) must be canned using pressure. High acid foods include apples, apricots and other stone fruit, berries, cherries, lemons, pears, tomatoes, pickles and sauerkraut. Low acid foods include asparagus, beets, carrots, corn, green beans, lima beans, rutabagas, and turnips.

Here is a link to more canning information from the National Center for Home Food Preservation.

Season All Season
Date 2012-06-14
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Keywords: Cornus kousa, Cornus florida, Powdery mildew diseases, Trees--Diseases and pests

PAL Question:

Where can I find information about dogwood hybrids, especially crosses between Cornus kousa and C. florida? Won't these trees be more resistant to the mildew affecting many dogwoods?

View Answer:

In addition to powdery mildew, many dogwoods can suffer with anthracnose. In his book Dirr's Hardy Trees and Shrubs (Timber Press, 1997), Michael Dirr mentions Rutgers Hybrids (which are a cross of the kousa and florida species of Cornus). These trees were developed at Rutgers University by Elwin Orton, and are resistant to dogwood anthracnose. Here is an article about these cultivars, written by Orton. This article from North Carolina State University Extension discusses powdery mildew resistance. Scroll to the second table at the end which charts cultivars and their resistance or susceptibility to powdery mildew.

Oregon State University provides information about each of the six hybrids of C. florida x C. kousa. Two of the trees on this list are resistant to powdery mildew.

Clemson University Extension offers further information about the insects and diseases affecting dogwoods.

Season All Season
Date 2008-01-17
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Keywords: Nurseries, Catalogs

PAL Question:

Where can I find a list of foreign nursery catalogs?

View Answer:

We have many foreign nursery catalogs at the Miller Library, as well as a list of what we have. Call us at 206-543-0415 or 206-897-5268 (every day but Sunday) and we can fax you the list. Or stop by and look at the catalogs. Library hours and directions to get here can be found here .

In addition, the Royal Horticultural Society has a plant finder online. Go to this link and follow the instructions. You can either search by plant or by nursery (name, region, or specialty).

The commercial website Dave's Garden has a section on mail-order gardening and nursery catalogs, including some foreign ones.

Season All Season
Date 2008-01-17
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Keywords: Acorus, Thalia, Typha latifolia, Sagittaria latifolia, Pontederia cordata, Cornus alba, Cornus stolonifera, Spiraea douglasii, Athyrium filix-femina, Lysichiton americanus, Scrophularia, Wetland plants, Carex, Native plants--Care and maintenance, Soil erosion, Iris, Deer

PAL Question:

We need some advice and we are hoping you can help. We would like to replant the banks of our fish pond and want to know what kinds of plants would hold a steep slope and be compatible with the fish and each other. We have a large deer and elk population and we get substantial amounts of rain. We like grass-type shrubs and we need a ground cover that will not take over and is evergreen.

View Answer:

From the research I have done, it seems that a pond with a sloping side is a very good idea, but if erosion is a serious issue, you may want to think about both plants and physical controls such as coconut fiber matting to stabilize the banks. The Brooklyn Botanic Garden's guide (1997), The Natural Water Garden, has a description of using coconut fiber tubes (also called biologs) laid horizontally along a bank, which can also be used as a secure planting medium for seedlings.

As far as deer-resistant plants which may work for your site, iris and spiraea appear to be unappealing to deer, so you might want to try some of the irises which prefer moist situations, such as Iris laevigata, and Iris versicolor (blue flag), as well as Spiraea douglasii (hardhack).

Other plants which may help with preventing erosion are Lysichiton americanum (skunk cabbage), Athyrium filix-femina (lady fern), Carex obnupta (sedge), and Cornus stolonifera (red osier dogwood) or C. alba (red twig dogwood).

Some grassy or reedy plants which do well as marginal (water's edge) plants include Acorus calamus 'Variegatus' (variegated sweet flag), Pontederia cordata (pickerelweed), Sagittaria latifolia (American arrowhead), and Typha latifolia (cattail). All of these are deciduous.

For evergreen plants, you could try Scrophularia auriculata 'Variegata' (water figwort), an evergreen perennial with cream-edged foliage. The flowers should be deadheaded to prevent self-seeding. Thalia dealbata (hardy canna) is evergreen, with long-stalked blue-green leaves and violet flower spikes.

Season All Season
Date 2006-03-20
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Keywords: Continuing education, Environmental education

PAL Question:

I am interested in finding a speaker in the Seattle area who can talk about environmental issues, from conservation, ecology, sustainable gardening, and so on. Can you help?

View Answer:

Here are some suggestions.

You can try contacting Seattle Tilth at 206-633-0451, or email them at tilth@seattletilth.org.
Their website address is http://seattletilth.org/.

Plant Amnesty may be able to help you (206-783-9813), or email them at info@plantamnesty.org.
You can find them online at http://plantamnesty.org/.

Other resources include:

King County (Washington) Master Gardeners maintain a speakers list which is updated annually. The speakers address a wide variety of gardening topics.

The Arboretum Foundation also maintains an annually updated speakers list.

Season All Season
Date 2008-01-17
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Keywords: Tulipa, Planting

PAL Question:

Will my Darwin hybrid tulips come back every year?

View Answer:

In his book Ask Ciscoe (Sasquatch Books, 2007), local garden expert Ciscoe Morris suggests planting Darwin and Empress hybrid tulips 12 inches deep (rather than the often recommended 6 inches) so that the bulbs will be less likely to divide and the squirrels less likely to dig them up.

Ann Lovejoy says much the same thing...plant tulips 10 inches deep, in a sunny spot, and in well-drained soil, and some are likely to return for several years. (See Seasonal Bulbs, 1995, p.16)

Season Fall
Date 2008-01-17
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Keywords: soil contamination, Wood preservatives, Pesticides and the environment

PAL Question:

We are thinking about putting in a retaining wall and a fence on our property, which is near a lake. Should we avoid using pressure treated wood? If so, what are some alternatives?

View Answer:

There are many reasons not to use treated wood for your fences and/or retaining walls. The chemicals most used to preserve wood---creosote (on railroad ties, among other things) and penta---were banned by the EPA in 1986 for indoor use and for many outdoor uses. The chemical used to pre-treat wood (CCA, a mixture of copper, chromium, and arsenic called chromated copper arsenate) has been shown to leach into the soil and to transfer to human skin through contact.

There are safe paints and preservatives for coating wood; there are safe types of pre-treated wood; some people use stone, cement blocks, or other materials instead of wood.

Below is lots of info about treated wood and alternatives.

Start with the page on the EPA site, which is full of information on treated wood. It includes a section on alternatives and some questions and answers about studies...look under Sealant Studies (Coatings).

If you find this too technical, try the next two links below.
The Natural Handyman website has good information.

Washington Toxics Coalition has a page about safe and unsafe paints and wood preservatives. Lots of background information on the toxicity of treated wood is included as well.

Season All Season
Date 2006-12-08
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Keywords: Plant inspection, Plant quarantine

PAL Question:

I will be transporting plants from Oregon to Washington to sell to the public. Are there any restrictions, such as quarantines, that are important to know about?

View Answer:

You should contact the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS).

The Oregon Department of Agriculture has information on plant exports, quarantines, and permits. There are also Washington State codes about the transportation of plants that can be found in Chapter 17.24 RCW, Insect Pests and Plant Diseases. You can then click on specific sections, such as 17.24.081, Prohibited acts.

Additionally, this site makes reference to the Washington Administrative Code and includes information about standards that apply to plants and pests. See Chapter 16-402 WAC, U.C. Davis Integrated Pest Management
North Carolina Cooperative Extension

Season All Season
Date 2008-01-17
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Keywords: Plum, Aphids, Prunus

PAL Question:

My prune tree has tons of aphids in the leaves (also a lot of ladybugs to eat them but I am not sure the ladybugs will win out). Do I need to try to rid the tree of the aphids? If so how?

View Answer:

The question of whether to control aphids in your prune tree really depends on how bad the infestation is and if the tree is otherwise healthy enough to outgrow them. Often infestations like aphids are a symptom of a larger problem. The tree may be stressed out by root competition from grass or too much or not enough water, too much or not enough nitrogen. A stressed out tree is attractive to aphids, who in turn attract lady bugs. My own mature prune tree gets covered in aphids every year. The leaves get distorted, and lady bugs come in droves. Some years I get a good harvest and some years I do not. I choose not to worry about it (I have other plants to fuss over). But if you feel the need to do something, see this website from WSU, then select Tree Fruits > Plum, Prune > Aphids.

Season All Season
Date 2008-01-17
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December 12 2014 11:33:49